Squeezing more k's from every litre...

[mainlander]

BB what are the specks on your truck? I run at 100km/hr and I'm only at 2000rpm. No turbo yet though.

Question for those that know. With larger than stock tires, is it just the spedo that needs adjusting of the tach as well?

Gerg, I should have kept that truck if you're getting that good efficiency out of it, but than again, I think my right foot is heavier than yours

I get about 600km's on 73L of fuel, not to bad at 12L/100km (19.6MPG). Certainly better than any gasser SUV on the market (except of course a hybrid) and way more fun to get around in. This also the other reason I own a TDI that gets me 41 MPG (again with my heavy foot).

I've got to loose me some weight in the right foot and it will all get better I'm sure.

[canucksafari]

Just the speedo needs to be adjusted. You can use this to work out the speed difference: Tire Size Calculator - tire & wheel plus sizing. Most people just use their GPS to keep track of the speed difference.

[sandcruiser]

speaking of saving $ on fuel.... I've seen it written that buying your fuel in the morning instead of the afternoon can make a very small difference in the amount of gasoline that ends up in your tank.

It's all temperature related- the idea is that when things are warmer, there is more vapor being scavenged from the filler nozzle instead of going into your tank.

There may also be a very very small change in fuel volume related to higher temps. But I'm guessing that underground tanks probably stay fairly constant temperature.

Regardless, it can't *hurt* to buy in the morning, and it could help.

[mainlander]

Thanks John for the link

I always thought it was about 10% I needed to add to the speedo.

Speedometer Difference: 9.599% too slow

[83bj60]

At an average of 85 kph mixed driving I went down to 10.5l/100, from 11.5 at 95kph. I can foresee my highway only driving reach all the way down to 9l/100 with skinny and tall tires at high pressure at an average of 85 kph. I just need to find super tall, skinny and light tires at this time.

As for slowing down traffic, tough luck. I won't be bullied. Besides, the minimum speed on the highway is 60kph, so that's legal.

Enough of making the speculators rich, the best way to refuse the outrageous fuel prices is to slow the traffic down. Now when the truckers finally catth up to it, we'll have a revolution on our hands...

[haryv]

Other ideas that I have yet to see discussed is putting in several removable belly pans that would streamline the airflow underneath the 60.

Cowling the rear wheel opening like the Honda Insite would also help.

Remove the roof rack or at least make it streamlined or collapable to cut down on the air turbulance. I have seen vortex generators that mount on the rear of the roofline but do not know if thay would work on the 60 or know if thay would help at all.

If the 60 could be lowered on demand then driving it a few inches off the ground would also reduce drag but know this is not possible with current configuration.


For in city driving weight is a killer on fuel economy. As was discussed lighten the truck as much as possible. I would not mind personally to replace all body panels, doors ect with carbon fiber/fiberglass replacments but have not seen any online.

And of course driving habits affect fuel economy so be very gental on the fuel pedal when excellerating .

[Dougal]

One of the worst things for fuel economy are your brakes. If you're driving in a way that you're constantly on the "stop" pedal then you're wasting fuel.
All the power to wear out pads, discs and drums comes from your fuel tank.

Regarding aero mods, they certainly help. But if you manage by some extreme modifications to drop the drag by 25%, you'd get exactly the same result by slowing down by 13.5%.
A vehicle travelling at 86.5km/h and a 25% more slippery vehicle travelling at 100km/h will have the same drag force.

[crushers]

weight
speed
rolling resistance
all have an effect on fuel milage BUT we also have to be reasonable about what we want to do to increase fuel milage.

belly pans are fine if you never go off road, never drive in deep snow. the flat lands of Canada would be good for these...anywhere else here and come winter you in deep snow and stuck.

this discussion is bring back all the stuff i learned WAAAY back in school.

stop and go traffic will kill your milage, probably why driving from Calgary to Edmonton (speed and wind resistance) returned the same fuel mileage as driving around rural ontario (stop and go).

[brownbear]

Originally Posted by mainlander

BB what are the specks on your truck? I run at 100km/hr and I'm only at 2000rpm. No turbo yet though.

235/85r16 tires...so 32.7 inches. 4.11 gears. H55f trans. 12 psi max turbo. 100 kmh is right around 2300-2400 rpm in 5th. 2300 is probably closer. 4th gear at 100 is 2600-2700 rpm. 105 kmh is 2500 in 5th.

90(55 mph) kmh is 2000 rpm. I like this speed. But find it's a little low for my boost. 5 psi at this one, unless I push on a hill.

Originally Posted by sandcruiser

Regardless, it can't *hurt* to buy in the morning, and it could help.

Fuel prices start high in the morning and chisel down thru the afternoon getting cheaper right up till after rush hour. Then at night around 12 they reset to high again. So it's been said

[sandcruiser]

hmmm...
if your fuel station is, in fact, changing their prices throughout the day, then the "fill er up early" stategy won't work as well.

I live in a land of controlled fuel prices-- its the same price no matter what time of day you stop, and the same price at every gas station. So time of day isn't a big factor.

Regardless of the pricing, it has also been suggested that if you fill up your tank at slower flow rates, you will also produce less vapor which means you'll end up with more fuel in your tank vs. going back through the vapor scavenging system. I suspect the difference is pretty minor (and has no bearing on me since we only get full serve here).

In the end, I think that the easiest and most signficant gains are made by keeping your tire pressure correct and accelerating less rapidly (both to go and to stop) as acceleration is really what eats up fuel more than anything else.

[brownbear]

look at the nuts on CleanMPG, An authoritative source on fuel economy and hypermiling it's a method called hypermiling. Not all of it I deem safe. Other than slowing down and enjoying the drive.

[Dougal]

Originally Posted by brownbear

look at the nuts on CleanMPG, An authoritative source on fuel economy and hypermiling it's a method called hypermiling. Not all of it I deem safe. Other than slowing down and enjoying the drive.

Hypermiling works best on petrol vehicles. Their throttle results in large pumping losses at low load cruising. So accelerating for short times at high throttle openings, then coasting between can reduce the average pumping losses and raise the efficiency quite a lot. But it's a frustrating and intensive way to drive.

On a diesel it still works if you can clutch in or pull the vehicle into neutral (illegal in some states apparently), but the gains aren't anywhere near as dramatic as your only saving is reducing engine rpm when in neutral, the pumping losses from the throttle body aren't significant and in most diesels don't exist.

235/85R16's should be just under 32".
Tire size calculator

[83bj60]

Originally Posted by Dougal

One of the worst things for fuel economy are your brakes. If you're driving in a way that you're constantly on the "stop" pedal then you're wasting fuel.
All the power to wear out pads, discs and drums comes from your fuel tank.

Regarding aero mods, they certainly help. But if you manage by some extreme modifications to drop the drag by 25%, you'd get exactly the same result by slowing down by 13.5%.
A vehicle travelling at 86.5km/h and a 25% more slippery vehicle travelling at 100km/h will have the same drag force.

Apart from testing our vehicles in a wind tunnel, are there any generic ways to reduce drag at the underside?

I recently read that truckers are now installing air dams at the bottom of their bumpers! What is the physical principle behind it? It seems so unintuitive to bolt on what essentially is a wall in front of the truck! Doesn't that create succion at the underbelly, which should create drag? I just don't get it...

[Dougal]

Originally Posted by 83bj60

Apart from testing our vehicles in a wind tunnel, are there any generic ways to reduce drag at the underside?

I recently read that truckers are now installing air dams at the bottom of their bumpers! What is the physical principle behind it? It seems so unintuitive to bolt on what essentially is a wall in front of the truck! Doesn't that create succion at the underbelly, which should create drag? I just don't get it...

Airdams make less air go through the lumpy underbelly and more over the (hopefully) smoother sides and top. Smoothing the underside will probably get you a better result but aerodynamics has still got a lot of "black art" in it.

If you've got a pyro and boost gauge, you can get a good feel for what makes your vehicle work harder and what makes it easier. It's not linear, but anything you do to reduce EGT and boost readings while in the same gear will reduce fuel.

[BURGER]

Originally Posted by Dougal

Hypermiling works best on petrol vehicles. Their throttle results in large pumping losses at low load cruising. So accelerating for short times at high throttle openings, then coasting between can reduce the average pumping losses and raise the efficiency quite a lot. But it's a frustrating and intensive way to drive.

On a diesel it still works if you can clutch in or pull the vehicle into neutral (illegal in some states apparently), but the gains aren't anywhere near as dramatic as your only saving is reducing engine rpm when in neutral, the pumping losses from the throttle body aren't significant and in most diesels don't exist.

235/85R16's should be just under 32".
Tire size calculator

I love how tire companies BS us. If we were take these numbers properly then those tires would/should be over 34.5 inches.

[Dougal]

Originally Posted by BURGER

I love how tire companies BS us. If we were take these numbers properly then those tires would/should be over 34.5 inches.

How do you figure that?
235x0.85 = 199.75mm.
199.75x2 = 399.5 = 15.7 inches of tyre.
15.7 inches of tyre plus 16 inches of rim = 31.7 inches.

[brownbear]

Originally Posted by Dougal

How do you figure that?
235x0.85 = 199.75mm.
199.75x2 = 399.5 = 15.7 inches of tyre.
15.7 inches of tyre plus 16 inches of rim = 31.7 inches.

yup thats correct for a metric tire calculation.

the manufacutre says 32 on their specs. They always round up. Some tires are bigger even thou they say the same spec as above. I have seen them listed as 32.7 in the charts from the manufacture. But I did not measure.
Here is Toyo's chart for interest. http://www.toyocanada.com/products/s...quest=Get+Data

[BURGER]

Originally Posted by Dougal

How do you figure that?
235x0.85 = 199.75mm.
199.75x2 = 399.5 = 15.7 inches of tyre.
15.7 inches of tyre plus 16 inches of rim = 31.7 inches.

OOPS. I must have been looking at my calculator through my glass crack pipe.

[TOBASH]

...
1) Stop and go driving turns fuel into heat on the brakes. Try to coast as much as possible. Try to accelerate gently and never hit the brakes as traffic ebbs and flows.

2) Alignment, alignment, alignment. Just a mild problem can rob 2 MPG

3) poor tire pressure.

4) Water injection or methanol injection can cool head temps and increase MPG

6) Don't bother with aerodynamics. FJ/BJ's have the aerodynamics of a brick.

7) Use cruise control. If you don't have it, install it.

8) make sure all brakes are fully unsprung and not hanging up.

9) synthetic oils and stuff can help, but maybe 1 mile per 10-20 gallons.

10) Clean injectors.

11) Tires with less aggressive tread. Crawling tires are meant for....crawling.

12) Stay in 2wd as much as possible.

13) Always be early for work. Air is cooler, traffic is lighter, and you are less stressed and aggressive. You use much less fuel.

14) Always relax on the way home. Traffic does not matter as there is no appointment and no client waiting. You will get home for dinner whenever. Just go with the flow.

You are still getting almost twice the mileage of a similar weight vehicle using petrol. That means Diesel fuel would need to be twice the price of gasoline before you would pay what most drivers pay, adjusting for mileage.

Best,

T

[freebie]

15. Make sure those damm e-brake cams on the fj and bj are not seized again!!

[Greg_B]

Just returned from a 833km road trip (just outside 100 Mile and back). Tootled up there with a highest average speed of 95kmph (2100-2200 rpm or so as it's got the Marks under/unders) and used 87 liters. I figure for a BJ74 that tips the scale over 5000lbs, 35" SSR's on steelies at 40psi, and bars on the outside that is pretty darn good. All GPS corrected.

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gb

[brownbear]

Sounds great to me. Lets see a pic of this truck. Not sure I have seen it yet on here.

[Fantom]

I see a lot of good ideas but no real modifications. After talking to Mike McT from Coastal Cruisers he came across something that's been used for a while in certain applications and he is doing a home brew of it to test it out. I can't remember the name of the device but it basically makes hydrogen gas and you insert it into the intake. Take a small container, insert stainless steel plates into it (kind of like a battery design) apply voltage, anywhere from 5 - 10amps 12VDC, fill with distilled water and use a (this part I don't recall too much) number of different things, like Baking soda, or I think Lime, or some other stuff. The end result is that you have this fine mist of mostly hydrogen which goes into your air intake (either pre or post turbo) and it improves several things, fuel economy and performance included. I don't know what the long term effects of it are, if there are any side effects, but apparently there are claims about a minimum of 10 - 20% increase of fuel economy and performance. I am not sure how I feel about a Hydrogen plant under my hood but I will do a bit more research on this.

[canucksafari]

Matt from what I hear of Mike's driving - "like a bat out of hell" I think was the phrase used - his simple solution would be less weight on the skinny pedal.

I am skeptic about this hydrogen plant for one reason. It takes energy to make energy. If you are running your alternator to make hydrogen, you are causing more drag on the engine and therefore using up energy. I think you would have to make a lot of hydrogen and I think you would likely be better off with the hydrocarbon of propane injection. The Aussies in the Patrol forum seem to be getting keener on this not only for the power increase but because if you set it up right you get better economy (provided your easy on the throttle). I was also reading somewhere a while ago that propane injection was first used a long time ago on naturally aspirated diesels. There was virtually no noticeble power increase but the economy of the engine improved. I will have to look for that aticle again.

[Dougal]

Originally Posted by Fantom

I see a lot of good ideas but no real modifications. After talking to Mike McT from Coastal Cruisers he came across something that's been used for a while in certain applications and he is doing a home brew of it to test it out. I can't remember the name of the device but it basically makes hydrogen gas and you insert it into the intake. Take a small container, insert stainless steel plates into it (kind of like a battery design) apply voltage, anywhere from 5 - 10amps 12VDC, fill with distilled water and use a (this part I don't recall too much) number of different things, like Baking soda, or I think Lime, or some other stuff. The end result is that you have this fine mist of mostly hydrogen which goes into your air intake (either pre or post turbo) and it improves several things, fuel economy and performance included. I don't know what the long term effects of it are, if there are any side effects, but apparently there are claims about a minimum of 10 - 20% increase of fuel economy and performance. I am not sure how I feel about a Hydrogen plant under my hood but I will do a bit more research on this.

Save your time and money. It's a scam.

[83bj60]

From a net energy expense versus energy produced (for the hydrogen), it certainly is and I second that.

But what about the claims of improving the diesel combustion process? There hasn't been much science devoted to test this theory but it's intriguing and I would love to see some real test results.

People tend to forget that, with any miracle fuel improver (especially those which present theories as fact and shore them up with human testimony) there is a very strong psychological component: as we expect fuel comsumption to improve, we also become more careful drivers and it's well known that the most important factor in fuel economy is driver behaviour...